1. Field of the Invention
The present invention relates to an anticancer drug or an anticancer agent for preventing and treating non-small cell lung cancer, comprising a substance for regulating the expression or activity of TM4SF4 (transmembrane 4 L six family member 4) as an active ingredient.
2. Description of the Related Art
Lung cancer is the second most frequent cancer among both men and women, which takes 15% of all cancers. According to the recent report made by American Cancer Society in 2011, at least 220,000 cases of cancer are diagnosed as lung cancer annually, among which approximately 70% of patients die which takes 27% of total death of cancer. Particularly, non-small cell lung cancer is a kind of carcinoma that generally includes all epithelial lung cancers except small cell lung cancer. Non-small cell lung cancer takes about 85%˜90% of total lung cancer. Non-small cell lung cancer is comparatively less sensitive to chemotherapy than small cell lung cancer. Stages of this cancer are divided by TNM classification which considers the size of tumor, diffusion to regional lymph node, and metastasis, etc. In the treatment of non-small cell lung cancer, the early stage of non-metastatic non-small cell lung cancer demonstrates very low sensitivity to chemotherapy and radiotherapy, so that ancillary chemotherapy using cisplatin comprising platinum is generally co-treated with surgical operation. However, when the cancer progresses to metastatic non-small cell lung cancer passing through the early stage, various chemotherapy and radiotherapy are used. Symptoms of non-small cell lung cancer are constant cough, chest pain, weight loss, nail damage, arthrodynia, shortness of breath, etc. In general, non-small cell lung cancer progresses slowly, so almost no symptoms are observed in its early stage. Therefore, it is as difficult to pick up this non-small cell lung cancer as to treat it. In most cases, once it transfers to the whole body, for example bone, liver, small intestines, and brain, it is then diagnosed. In spite of high incidence rate and high death rate, any efficient drug or treatment method to overcome non-small cell lung cancer has not been developed, yet, emphasizing the necessity of it. Non-small cell lung cancer is divided into a few sub-groups according to the size, the shape, and the chemical composition of cancer cell, which are represented by adenocarcinoma, squamouse cell carcinoma, and large cell carcinoma. Adenocarcinoma is a kind of lung cancer that is most frequently observed which takes at least 40% of total lung cancer. Adenocarcinoma is usually developed in outer region of the lung and progresses more slowly than other lung cancers. However, adenocarcinoma shows high tendency of metastasis in the early stage and high radioresistance. Squamouse cell carcinoma is a kind of non-small cell lung cancer that takes 25˜30% of total lung cancer. It starts in early version of cells forming airway. This cancer occurs highly in smokers. Large cell carcinoma can be developed in any region of the lung and takes 10˜15% of total lung cancer. Progression rate of this cancer is as fast as that of small cell lung cancer, which makes the treatment still difficult.
Cancer development starts from abnormal cell growth. When any gene, for example the gene playing a certain role in cell cycle or the gene that is responsible for DNA repair mechanism for auto-elimination of mutation, is mutated, tumor suppressor gene is inactivated or oncogene is activated, resulting in the abnormal cell growth or abnormal cell proliferation. For instance, non-small cell lung cancer starts with the mutation of EGFR (epidermal growth factor receptor) and then keeps being activated without its ligand EGF (epidermal growth factor), which is abnormal proliferation or growth (non-patent reference 1). PI3K (phosphatidylinositol 3-kinases)-Akt (protein kinase B) pathway is an important intracellular signal pathway for cell proliferation and migration. In cancer cells, the PI3K-Akt signal pathway is always activated, unlike in normal cells. The most characteristic factor of cancer cell is the over-expression of MMP (matrix metalloprotease). MMP is a protease that degrades extracellular matrix whose activity is essential for cell migration, intravasion, extravasion, angiogenesis, and metastasis. MMP is generally expressed only when necessary for tissue remodeling or wound healing. However in cancer cells, MMP is over-expressed to mediate cancer cell migration, cancer cell growth, and metastasis (non-patent reference 2). Unlike normal cells therefore, cancer cells are excessively grown to be transferred to other organs, which means cancer cells spread to the whole body to destroy normal tissues unless treated.
TM4SF4 (transmembrane 4 L six family member 4) is a kind of cell membrane protein called tetraspanin, which is a member of transmembrane 4 superfamily of L6 (non-patent reference 3). Cell membrane protein belonging to tetraspanin superfamily is involved in many biological systems relating to diseases including cancer, suggesting that it is involved in a wide spectrum of various processes occurring in cells, according to a previous report. Most previous studies stated that the expression of tetraspanin is involved in the regulation of cancer development marker and is at least believed to be involved in the malignancy of cancer cells (non-patent reference 4). Transmembrane 4 L6 superfamily includes L6, L6D, TM4SF4, and TM4SF5. The whole structures of them are similar and the difference is only made by C-terminal. TM4SF5 is closely related to tumorigenesis and metastasis (non-patent reference 5-6). It has also been reported that TM4SF4 is involved in rat pancreas differentiation and hepatocyte regeneration in the developmental stage (non-patent reference 7-8). TM4SF4 has also been reported to belong to the candidate gene group that shows low expression in normal cells but high expression in adenocarcinoma cells (non-patent reference 9). Nevertheless, there is no report yet in relation to the accurate function of TM4SF4. In particular, there are no studies so far conducted with human cells and cancer cells to disclose the specific function of TM4SF4.
Thus, the present inventors tried to disclose the function of TM4SF4 in cancer cells. As a result, the inventors confirmed that the expression of TM4SF4 varies from the type of non-small cell lung cancer and the control of TM4SF4 expression might affect radioresistance, cell growth, metastasis, and infiltration of non-small cell lung cancer cells. Particularly, adenocarcinoma cell lines (A549, Calu-3) showed higher TM4SF4 expression, compared with other cell lines of non-small cell lung cancer. When the expression or activity of TM4SF4 was suppressed by using TM4SF4 antibody or siRNA, not only cancer progress, cell growth, metastasis, and infiltration, but also radioresistance was all reduced. In the meantime, in other non-small cell lung cancer cell lines except adenocarcinoma showing comparatively low TM4SF4 expression, when the expression of TM4SF4 was increased by using TM4SF4 expression vector, cell growth and radioresistance were decreased. The present inventors further confirmed that the regulation of TM4SF4 expression and activation brought the above effect by regulating the activity of IGF1R/PI3K-Akt/NK-κB and the expression of MMP in cancer cells. As a result, the present inventor completed this invention by confirming that the pharmaceutical composition that is able to reduce the expression of TM4SF4 was effective in preventing and treating adenocarcinoma among non-small cell lung cancers, and the pharmaceutical composition that is able to increase the expression of TM4SF4 was effective in preventing and treating non-small cell lung cancers except adenocarcinoma and was more effective when co-treated with radiotherapy.